from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
from config import settings

DATABASE_URL = settings.database_url

engine = create_engine(DATABASE_URL)  
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)  

Base = declarative_base()  # 生成 Base 类，所有模型都继承它
